Apparatus for desuperheating vapor



Nov. 19, 1940. l H. H, GQRR'IE 2,222,348

APPARATUS FOR DESUPERHEATING ,VAPOR Filed July l5, 1936 Patented Nov.19, 1940 UNITED STATES APPARATUS FOR DESUPERHEATING VAPOR Harvard H.Gorrie, Cleveland Heights, Ohio, as-

signor to Bailey Meter Company, a corporation of Delaware ApplicationJuly 15., 1936, Serial No. 90,695

9 Claims.

This invention relates to apparatus for partially or completelydesuperheating vapor.

It is well known to desuperheat a flowing stream of vapor, such as steamfor example, by

providing a spray ring or nozzle having a plurality of fine openingsthrough which water flows in an atomized or broken up condition into thesteam. Such a system is satisfactory when the pressure drop across thefine openings corre- 10 sponds to that for which they were designed.

However, if used on a variable steam flow, necessitating throttlingofthe water supply in order to maintain a constant temperature of thedesuperheated steam, the arrangement is not satis- R5 factory as thewater then is not atomized or broken up but leaves the openings in asolid stream so that intimate mixing with the steam is not obtained. Ithas been found in commercial practice that a desuperheater designed toproperly desuperheat a given maximum steam flow will not operatesatisfactorily if the steam" flow is reduced below 50% of the saidmaximum.

It is therefore one object of my invention to provide apparatus fordesuperheating vapor whereby a nely atomized spray is obtained over awide range in output.

Further, in accordance with my invention changes in the temperature of.the desuperheated vapor are anticipated and the output of thedesuperheater modied accordingly before such changes in temperatureactually occur.

My invention further provides for con-trolling the output of adesuperheater conjointly from the temperature of the desuperheated Vaporand `the rate of flow thereof.

My invention further provides for varying the output of a desuperheater,both proportionately to changes in the temperature of the desuperheatedvapor and to the amount of deviation of the temperature from apredetermined or desired magnitude.

It should be understood that the term desuperheated vapor ordesuperheated steam as used in this specification applies to vapor 'orsteam which may be only partially desuperheated and not necessarily tozero degrees of superheat.

In the drawing:

Fig. 1 illustrates diagrammatically an embodiment of my invention.

Fig. 2 is an elevation view to larger scale of the spray nozzle shown inFig. 1.

Fig. 3 is a cross sectional View of the spray nozzle along the lines 3-3of Fig. 2 in the direction of the arrows.

u In accordance with the present invention there is provided a conduit Ito which superheated vapor is admitted so that it flows through theconduit in the direction indicated by the arrow.

Extending into the conduit is a water jet or spray nozzle 3 pointingupstream with respect to 5 its discharge end II, although the directionof discharge may be reversed if desired. Water is supplied the nozzle 3under a pressure greater than that of the vapor to be desuperheated,

through a pipe 5 leading from any suitable m source, such as thedischarge conduit 6 of a centrifugal pump I to which Water is admittedthrough an inlet 8. It will be understood that the arrangement I haveshown for providing desuperheating fluid to the nozzle 3 is merelyillus- 15 trative and that any suitable source may be used.

The nozzle 3 as shown in Figs. 2 and 3 comprises a circular chamber ,9provided with an axially located aperture or orice I0 through which thedesuperheating fluid, such as water, 20 is discharged into the stream ofvapor to be desuperheated. Water is admitted to the chamber 9 from thepipe 5 through an inlet connection II and port I2 tangentially withrespect to the circular wall of the chamber 5. Water enter- 25 ing thechamber 9 and not discharged through the orifice ID is Withdrawn throughan axially located secondary outlet connection I3 leading to a source ofrelatively low pressure, which may be for example the inlet 8 of thepump l. 30

The port I2 is arranged so that water passes therethrough at highVelocity and sets up in I.the chamber 9 a rapid rotary motion whichcauses the water to be discharged through the orice I0 in the form of aspray or nely atom- 35 ized condition. The rate of discharge through theorifice I 0 may be varied by throttling the flow through the secondaryconnection I3. With the secondary connection closed, all the wateradmitted through the port I2 is discharged through the orice I0. Withthe secondary connection partially restricted some of the water will bedischarged therethrough, decreasing the discharge through the orice I0proportionately. Variations in the rate of discharge through the sec- 45ondary connection I3 does not, howeverylaiect the velocity through thetangential port I2 or the rapidity of the rotary motion set up in thechamber 9. Inasmuch as the quality of the spray produced by the orice I0depends substantially 50 entirely upon the rate of rotation of the massof Water within the chamber 9 it follows that Variations in thedischarge through the secondary outlet I3 and'corresponding variationsin the discharge to the orice I0 will in no way affect the 55 chamber 9,which remains substantially constant a decrease in fluid pressure thediaphragm motor 'temperature of the desuperheated steam may usuperheated steam temperature from the prede- .;f.. i free end of theBourdonl tube I'I in an upward quality of the spray established. Inother words, the neness or quality of the spray is determined by thevrotary motion of the water within the Pivotally connected to the freeend of the of a pilot valve 20 preferably of the type forming thesubject matter of a United States patent `to Clarence Johnson, PatentNo. 2,054,464, dated September 15,1936. Suitable iiuid under pressure,such as compressed air, is admitted to the pilot through an inlet port2| and is conducted at al1 times, whereas the rate of discharge into theconduit lI is determined by the pressure drop across the orifice I0,which in turn is controlled by the throttling of Ethe secondary outletI3. I have found-that the water will leave the nozzle to waste ports ateither end of the pilot valve 'eiciently atomized, from a maximum flowobthrough an axially located cylindrical passagetained with thesecondary outlet I3 closed down Way extending longitudinally -throughthe pilot to' approximately 10% or less of that maximum. valve. Verticalpositioning of the valve mem- It is apparent from the foregoing that theber I9, which carries suitable lands, modifies the magnitude of thefluid pressure effective at be held at some predetermined desired valueregardless of changes in the rate of flow thereof by varying the iiowthrough the secondary outlet in accordance with deviations in thetemperavalve member there is a pressure of denite magnitude, Which forconvenience term aloading pressure, established at the outlet port. Withture from the predetermined or desired value. y the valve member I9 atthe lowest position within its range of movement a loading pressure ofminimum magnitude is established at the outlet It is further apparentthat the throttling of the flow through -the secondary outlet vwill haven o` effect upon the eilcient atomizing of the water spray, so that thesteam will be uniformly desuperheated to the predetermined or desiredtemperature.

In Fig. 1 I show a valve I4 connected in the secondary outlet I3 forthrottling the ow therethrough. The valve I4 is arranged to beVariations in loading pressure established at actuated by a pressuresensitive diaphragm the outlet port 22 are effective for actuating themotor I5. As shown, upon an increase in uid diaphragm motor I5 to causeprOPOrtiOrlate pressure of given amount the diaphragm motor mOVementS 0fthe valve |4 Accordingly, upon acts to position the valve I4 in aclosing direc# an increase in the temperature of the desupertion aproportionate amount. Conversely, upon heated steam the valve member I9,through the agencyfof the Bourdon tube I'I, will be positioned upwardlya proportionate amount eiecting a like Iposition within its operatingrange a loading pressure of maximum magnitude is established.

sure will vary proportionately ywith the axial positioning of the valvemember.

acts to position the valve a proportionate amount in an openingdirection. change in thev loading pressure at the outlet In oneparticular aspect my invention conport 22. This Change in loadingpressure transtemplates4 establishing a fluid pressure varying mitted t0the diaphragm motor l5 through deboth in accordance with changes intemperature vices later to be described actuate the motor to of thedesuperheated steam and the amount of position the valve Iii in aclosing direction an deviation of the actual temperature from the amountproportional to the increase in desuperdesired or predeterminedtemperature, and heated Steam temperatura A greater proporutilizing thefluid pressure to position the tion of the water transmitted to thenozzle 3 will diaphragm motor I5. Accordingly, upon a, then bedischarged through the orifice I0 tending change in temperature d thedesuperheated to restore the temperature of the desuperheated steam,regardless of whether the change is to- Steam i0 the desired Value. If110W the tem ward or away from the predetermined value, an perature ofthe desuperheated steam should deimmedlate and proportionate change ismade Grease, the loading pressure transmitted t0 the in the flow throughthe secondary outlet lain diaphragm motor i5 will decrease proportionasense to produce a temperature change of aiely, eie'ting a movement 0fthe Valve I4 in the desuperheated steam in opposite direction. anOpening direCtiOn, thus decreasing the diS- Continuously, however, theow through the Charge 0f Water irltO the COIlduit It iS apsecondaryoutlet I3 is modified at a rate propor- Parent that the aDDaratuS S fardescribed Will tiona1 to the amount of deviation of the deact tomaintain a denite rate of discharge of water for every temperature ofthe desupertermined value so that the temperature is main- .heatedSteamtained substantially at the predetermined value T0 P/llovide an.ample Supply of pressure uid without overshooting or hmm gr/rgafggfnforoperating the diaphragm motor I5 and changes in thefr-,ofiy/fsteam tbe`de further to provide means for producing a consuperheated or changes1n the degree of supertinuous change in the rate of ilow through theheat thereof. secondary outlet I3 at a rate proportional to the I willnow describe the apparatus provided for amount of deviation of theactual value of the producing the uid pressure for actumm'lgv thedesuperheated steam temperature from the predlaphragm motor l5, Thetemperature of the determined value I preferably interpose betweendesuperheated steam is measured by a therthe outlet port 22 and thediaphragm motor I5 a mometric system comprising a bulb IB extendingstandardizing relay 23 0f the type flming the into the conduit l beyondthe nozzle 3 and consubject matter of my copending application, neotedt0 a Bourdon tube I1 by a capillary I8. Serial No. 8047, filedin theUnited States Patent An increase in temperature of the desuperheatedOlce February 25, 1935. steam eiects a proportionate movement of theWithin the relay 23, hich is shown in cross section, is a chamber 24separated by a pressure sensitive diaphragm 25 from a chamber 26 open tothe atmosphere through a port 21. Below a pressurel tight partition 28is a further pair of direction. Conversely, a decrease in A superheatedsteam temperature effects a proportionate positioning of the Bourdontube in a downward direction.

Bourdon tube I1 is the movable valve member I9 an outlet port 22 so thatfor every position of the port. With the valve member at the highestBetween these two extremes the loading pressitive diaphragm 3|, andconnected with each other through a passageway 32 in which is located anadjustable throttling valve 33 for controlling the rate at whichpressure iiuid will 5 bleed from one chamber to the other. Secured tothe diaphragms 25 and 3| is a movable member 32 engaging at its lowerend a fulcrumed normally horizontal member 33A carrying dependingextensions for operating a normally closed pressure iiuid admissionvalve 34 when displaced from the horizontal in one direction, and anormally closed pressure fluid exhaust valve 35 when displaced in theopposite direction. The pressure fluid, such as compressed air, admittedthrough the valve 34 may be derived from any suitable source (not shown).Secured to the upper end of the movable member 32 is a manuallyadjustable tension spring 36 for urging the lmember 32 upwardly.

The outlet port 22 of the pilot 20 is connected to the chamber 24through a pipe 31 so that loading pressures established by the pilotvalve are immediately effective therein and produce a proportionatedownwardly acting force on the di- 25 aphragm 25.

Now assuming for the moment that the throttling valve 33 is closed, theforce acting against the diaphragm 25 will position the member 32downwardly opening the admission valve 34 and permitting the pressurefluid to enter chamber 30. As the pressure within the chamber 3Uincreases the force acting upwardly against the diaphragm 3| willincrease, and when it is equal to or stands in predetermined relation tothe 35 force acting on the diaphragm 25 the member 32 will move upwardlyclosing the admission valve 34. Conversellhupon a decrease in pressureWithin the chamber 24 the member 32 will move upwardly opening theexhaust valve 35, permitting pressure fluid to escape from the chamber3D until the force acting upwardly on the diaphragm 3| is again equal tothat acting downwardly on the diaphragm 25. Thus for every pressurewithin the chamber 24 there will be a corresponding pressure Within thechamber 30. While a change ,in pressure of given amount Within thechamber 24 will result in an equal change in pressure within chamber 30,the absolute value of the pressure within the chamber 30 may bediierentfrom that within chamber 24 and is controlled by the adjustmentof the spring 36.

If now the throttling valve 33 is partially opened so that pressurefluid may pass at a relatively slow rate between chambers 29 and 3U, up-

on a change in pressure within the chamber 24 a proportionate changewill immediately occur in chamber 30. Thereafter, however, in place ofthe valves 34 and 35 remaining closed and the pressure within chamber 30constant, pressure uid will pass between the chambers destroying theequilibrium forces acting upon the diaphragms 25 and 3| and occasioninga further change in pressure within the chamber 30. Such further changewill cause a further passing of uid between the chambers 29 and 3| andresult in a still further change in pressure within the chamber 30.While I have described the operation and steps, it is apparent that thechange in pressures within the chambers 29 and 30 will be gradual andcontinuous.

In operation the spring 36 is initially adjusted so that with theloading pressure existing within the chamber 24 corresponding to thatproduced when the temperature of the desuperheatedl steam is at thepredetermined value, and the throttling valve 33 open so that equalpressures will exist in chambers 29 and 30, the valves 34 and 35 areclosed. The throttling valve is then moved to a partially closedposition, the exact position being determined by the constants of thesystem, such as speed of response, lag, etc. Thereafter upon a change inloading pressure Within the chamber 24 an immediate and proportionatechange will occur in chamber 30, which will be followed by a continuingsecondary change due to the regenerative action between chambers 29 and30 as hereinbefore described. It is apparent that therate of thesecondary change will be proportional to the diierence in pressurebetween chambers 29 and 30, which will in turn be proportional to thedeviations in temperature from the desired value. It is further'apparent that only when the temperature is at the predetermined valuewill the pressure within the chamber 30 remain constant. When at anyother value the pressure therein will continually change, and in sensedependent upon the direction of deviation of the temperature from thepredetermined value.

The pressure within the chamber 30 is transmitted through a pipe 38 to achamber 39 of an averaging relay 40 somewhat similar to thestandardizing relay 23. Changes in `pressure within the'chamber 39produce proportionate changes in pressure within the chamber 4|connected to the diaphragm motor |5 by a pipe 42.

In operation, assuming the desuperheated steam temperature to be at thepredetermined value, upon a change in temperature of given amount, forexample an increase, a proportionate change in loading pressure withinthe chamber 24 will occur which will produce an immediate andproportionate change in the pressure within the chamber 30, which willbe transmitted through the relay 40 to the diaphragm motor I5. Thediaphragm motor will operate the valve I4 in a closing direction todecrease the flow through the secondary outlet, thus increasing .thevalve |4, -or in other words in a direction tending to prevent suchreturn. However, the secondary continuing response will still act toclose the Valve so `that the return of the temperature to thepredetermined value will be asymptotically and overshooting or huntingwill be avoided.

Upon a decrease in temperature below the desired value the converseaction will occur, the valve I4 rst being positioned in an openingdirection an` amount proportional to the decrease in temperature, andthereafter continuously -positioned in an opening direction at a rateproportional to the amount the temperature is below the predeterminedvalue. It is apparent that in general the control responds upon a changein temperature to give an immediate and proportionate correction in adirection to prevent the change, and to give a continuing correction ina direction to restore the temperature to the desired value. The rst orimmediate response is nary operating conditions give satisfactoryresults. It is to be noted, however, that it is necessary for adeviation 'in temperature of the desuperheated steam to occur before acorrection is made to restore the temperature to the predeterminedvalue. Under widely varying rates of steam flow resulting vin sudden andextreme changes in desuperheated steam temperature the allowable limitsof temperature deviation from the predetermined value may be exceeded.To prevent such an occurrence my invention further contemplatesanticipating changes in temperature andcorrecting the rate of dischargeof water into the superheated steam before such changes actually occur.In general, the control acts to vary the discharge through the orice I0in proportion to changes insteam flow. If due to valve or nozzlecharacteristics or other causes the change in Water discharge so made isnot exactly correct to maintain the desuperheated steam temperature atthe predetermined value then the control sensitive to the temperature ofthe desuperheated steam will continually modify the water dischargeuntil the predetermined temperature is restored.

To position the valve I4 to vary the rate of discharge through theorifice I0 in accordance with changes in steam ow I introduce into achamber 43 of the averaging relay 40a loading pressure proportional tothe rate of' steam flow.

-Thus upon an increase in steam flow, for example, the loading pressurewithin the chamber 43 is increased proportionately, causing alike'increase in pressure within the chamber 4|, which is transmitted tothe diaphragm motor l5 and serves to position the valve I4 in a closingdirection, thereby increasing the discharge' of water into the conduitl. Upon a decrease in the rate of steam flow the reverse action takesplace, the loading pressure within the chamber 43 decreasingproportionately, causing a like movement of the valve i4 in an openingdirection, thereby decreasing the rateof discharge of water through theorifice l 0.

If correct correspondence has been maintained during and after `suchchanges, between water discharge and rate of steam ow, and there hasbeen no change in superheated-steam tempera'- ture, then thedesuperheated steam temperature will remain at the predetermined value.If, however, such correspondence is not exactly maintained, then arelatively small change in desuperheated steam temperature will occur,which will readily be corrected by the control sensitive todesuperheated steam temperature 'as hereinbefore described. g

The loading pressure ,established Within the chamber 43 and varying inaccordance with' changes in steam ow is produced by a pilot valve 44havingv a valve member 45 vertically positioned by an indicator arm 46of a rate of iiow meter 4].

The flow meter 41 may be of the type shown and described in UnitedStates Patent 1,123,164 to Bailey, and comprises essentially 'a bell 48sealed ina liquid such as mercury indicated at 49 and verticallypositioned therein in accordance with the differential pressure producedby a restriction such as an orice 50 in the conduit l. As known, thedifferential pressure produced by a device such as the orifice bears aquadratic relation to the rate of ow. In order that the indicator arm 46will be positioned directly proportional to changes in ow rather thandifferential pressure the bell 48 may be provided as shown with a wallof varying thickness, so that it will be positioned proportional to thesquare root of the differential pressure rather than in directproportion.

The pilot valve 44 is similar to the pilot 20, in-

asmuch however as the loading pressure pro-` duced thereby shouldprogressively increase as the valve member 45 moves downwardly, con-Anection from the chamber 43 is made to an outlet port' 5| located belowthe inlet port 52. Thus What I claim as new, and desire to secure byLetters Patent of the United States is:

1. A desuperheater comprising a chamber, an orifice of constant arealocated in said chamber for discharging desuperheating iiuid directlyinto a :lowing stream of vapor to be desuperheated,.a

discharge connection tov said chamber for withdrawing desuperheating uidtherefrom, and means for controlling the rate of ow of uid through saiddischarge connection conjoitly responsive to the rate of ow of the vaporto be desuperheated and the temperature of the desuperheated vapor.

2. A desuperheater comprising a chamber, an orice located in saidchamber for discharging desuperheatng fluid into a owing stream of vaporto be desuperheated, a discharge connection to said chamber forwithdrawing desuperheating fluid therefrom, regulating :means of therate of flow through said discha-rge connection, and control means forsaid regulating means'comprising means for establishing a first uidpressure in accordance with the temperature of the desuperheated vapor,means responsive to changes in said rst fluid pressure for establishingimmediate proportional changes in a second. fluid pressure andcontinuing changes therein upon departure of the first fluid pressurefrom a predetermined value,

-and means actuated by said'second fluid pressure for controlling saidregulating means.

3. A desuperheater comprising a chamber, an orice in a .wall of saidchamber for discharging desuperheating uid into a flowing stream of thevapor to be desuperheated, a discharge connection to said chamber forwithdrawing desuperheating fluid therefrom, means responsive to thetemperature of the desuperheated vapor, and means actuated by said lastnamed means for producing immediate changes in the rate of flow of fluidthrough said ldischarge connection in proportion to changes in the`temperature of the desuperheated vapor and continuous changesproportional to the deviation of the temperature of the desuperheatedvapor from a predetermined value.

4. A desuperheater comprising a chamber, an orifice in a wall of saidchamber for discharging desuperheating fluid into a flowing stream ofvapor to be desuperheated, a discharge connection to said chamber forwithdrawing desuperheating fluid therefrom, means for producing a firstfluid pressure in accordance with the temperature of the desuperheatedvapor, means for establishing a second fluid pressure in accordance withthe rate of flow of the vapor to be desuperheated, means forestablishing a third uid pressure in accordance with the algebraic sumof the first and second fluid pressures, and regulating means of therate of flow of fluid through said discharge connection under thecontrol of said third fluid pressure.

5. A control system for a de-superheater comprising in combination,means for establishing a first fluid pressure in accordance with therate of flow of vapor to the desuperheater, means for establishing asecond fluid pressure in accordance with the temperature of thede-superheated vapor, means under the control of the first fluidpressure to regulate the rate of `flow of the desuperheating fluid indirect ratio to the rate of flow of the vapor to be de-superheated, andmeans under the control of the second fluid pressure for varying theratio between the rate of flow of vapor and desuperheating fluid.

6. In a control system for a desuperheater in combination, regulatingmeans of the rate of flow of desuperheating fluid, control means forsaid regulating means comprising means for establishing a first fluidpressurev in accordance with the temperature of the desuperheated vapor,means responsive to changes in said first iluid pressure forestablishing immediate proportional changes in a second fluid pressureand continuing changes therein upon departure of the first fluidpressure from a predetermined value, and means actuated by said secondiluid pressure for controlling said regulating means.

'7. In a control system for a desuperheater, wherein a desuperheatingfluid is used to desuperheat a flowing uid to be desuperheated, in

pressure corresponding to the temperature of the desuperheated vapor,means for establishing a second fluid pressure corresponding to the rateof flow of `vapor to be desuperheated, means for establishing a thirdfluid pressure corresponding to the algebraic sum of the first andsecond fluid pressures, and regulating means of the desuperheating-fluidactuated by the third fluid pressure.

8. lIn a, control system for a desuperheater wherein a desuperheatingfluid is used to desuperheat a flowing fluid to be desuperheated, incombination, means for establishing a first fluid pressure correspondingto the temperature ofthe desuperheated vapor, means for establishing asecond fluid pressure corresponding to the rate of flow ofdesuperheating fluid, means under the control of the first fluidpressure for-producing changes in the second fluid pressure proportionalto changes in the rst fluid pressure, and regulating means of thedesuperheating fluid actuated by the second fluid pressure.

9. In a control system for a desuperheater wherein a desuperheatingfluid is used to desuperheat a flowing fluid to bedesuperheated, incombination, regulating meansl of the rate of flow of the desuperheatingfluid comprising means for establishing immediate and proportionalchanges in a fluid pressure in accordance with changes in thetemperature of the desuperheated vaporl and continuing changes in thefluid pressure in accordance with the departure of the temperature ofthe desuperheated vapor from a predetermined Value, and regulating meansof the desuperheating fluid under the control of said fluid pressure.

HARVARD H. GORRIE.

